Glass materials as a structural material may require mechanical strength against compression or buckling, shear or break or the like. For example, in an image display panel of a type in which two flat insulating substrates are bonded and the inside of them is decompressed or evacuated, spacers (gap holding members) intervene between the insulating substrates to hold the gap between the insulating substrates at a predetermined value. The following description will be made assuming that such spacers are used, but it goes without saying that the present invention is not limited thereto.
Various types are known as an image display using an image display panel formed by bonding two flat insulating substrates (a back substrate and a front substrate), or a so-called flat-type display. For example, attention has been focused on an image display panel which has electronic sources arranged in a matrix (FPD: flat panel display). Well-known examples of those image display panels include an FED (Field Emission Display) panel and an electron emission display panel using small cold cathode which can be integrated. Cool cathodes of the type include a Spindt electronic source, a surface conductive electronic source, a carbon nanotube electronic source, an MIM (Metal-Insulator-Metal) type including a stack of metal, insulator, and metal, an MIS (Metal-Insulator-Semiconductor) type including a stack of metal, insulator, and semiconductor, and a thin film electronic source including metal, insulator, semiconductor, and metal.
In the electron emission FPD, a back substrate including electronic sources described above is bonded to a front substrate including a fluorescent material layer and an anode providing an acceleration voltage for causing electrons emitted from the electronic sources to strike the fluorescent material layer, and the internal space between the opposed substrates is sealed at a predetermined reduced pressure or a vacuum. The back substrate includes a number of electronic sources arranged in a matrix. The front substrate includes the fluorescent material layer and the anode forming an accelerating voltage for forming an electric field for causing electrons emitted from the electronic sources to strike the fluorescent material layer.
Each of the electronic sources forms a pair with an associated fluorescent material layer into a unit picture element. In general, unit picture elements for three colors, that is, red (R), green (G), and blue (B), form a single picture element (color picture element or pixel). For the color picture element, a unit picture element is also called a sub-picture element (subpixel).
The gap between the back substrate and the front substrate is held at a predetermined interval by members (gap holding members, hereinafter referred to as spacers) called partitions arranged to support both substrates in a display area. The spacer is formed of a plate-shaped body made of insulating material such as glass and ceramic or a member having some electrical conductivity. The spacer is disposed in association with a plurality of picture elements at positions where they do not prevent the operation of the picture elements.
Patent Document 1 has disclosed a display in which a back substrate and a front substrate are used with a reinforcing plate and a high-vacuum container is formed by frame glass. Patent Document 2 has shown a disclosure of lead-free glass with a low melting point as frit glass for use in sealing a glass plate. Patent Document 2 has disclosed the lead-free glass with a low melting point containing B2O3 or V2O5, BaO instead of PbO—B2O3 which may cause environmental pollution.
Patent Document 3 has disclosed V2O5—TeO2 glass.
(Patent Document 1)JP-A-2000-206905(Patent Document 2)JP-A-2003-192378(Patent Document 3)JP-A-2004-250276